photosystem I


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Related to photosystem I: Photosystem II

photosystem I

[′fōd·ō‚sis·təm ′wən]
(biochemistry)
One of two reaction sequences of the light phase of photosynthesis in green plants that involves a pigment system which is excited by wavelengths shorter than 700 nanometers and which transfers this energy to energy carriers such as NADPH that are subsequently utilized in carbon dioxide fixation.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Modulation of photosystem II chlorophyll fluorescence by electrogenic events generated by photosystem I. Bioelectrochemistry, v.
The higher [F.sub.0]/[F.sub.m] indicates that the initial rate of reduction of the plastoquinone (Qa) was higher than the rate of plastoquinone reoxidation by b (Qb) and the activity of photosystem I (PSI) when plants were exposed to higher concentrations of NaCl.
PSII Photosystem II: A complex of pigments and proteins that transfer electrons from water to Photosystem I PSI Photosystem I: A complex of pigments and proteins that transfer electrons to NADPH Reaction Center Special chlorophyll a molecules in a photosystem that are actually involved in the transfer of elec trons, and thus chemical reactions, in photosynthesis Redox Reactions Chemical reactions involving simultaneous reduction and oxidation of chemical substances.
While screening DNA sequences in water samples collected during Craig Venter's Global Ocean Sampling Expedition, his team discovered seven more photosynthesis genes coding for a complex of proteins collectively named photosystem I.
In normal photosynthesis, photosystem I grabs electrons from proteins higher up in the photosynthesis chain reaction.
The bacteria genes co-opted by the marine viruses are part of a group, or "cassette" of genes called photosystem I.
Photosystem I and another gene cassette called photosystem II genes are essential to the first steps of photosynthesis, absorbing energy from light and transforming into a form that can be used to fuel further reactions in the process.
During photosynthesis, plants have two photosystems that work in tandem: photosystem I and photosystem II.